Manage disallow_iframe_embed
Manage disallow_iframe_embed

disallow_iframe_embed can be used to prevent Horizon from being
embedded within an iframe. Legacy browsers are still vulnerable
to a Cross-Frame Scripting (XFS) vulnerability, so this option
allows extra security hardening where iframes are not used in
deployment

Change-Id: I2fe6b243250608b340ee555062060dbdad1a49c4
Depends-On: I5c540e552efe738bdec8598f9257fa22ae651a76
Closes-Bug: #1641882

openstack/tripleo-heat-templates,dprince/tripleo-heat-templates,dprince/tripleo-heat-templates,openstack/tripleo-heat-templates